shotgun/external_libs/libgdtoa/g_ddfmt.c

   1 /****************************************************************
   2
   3 The author of this software is David M. Gay.
   4
   5 Copyright (C) 1998 by Lucent Technologies
   6 All Rights Reserved
   7
   8 Permission to use, copy, modify, and distribute this software and
   9 its documentation for any purpose and without fee is hereby
  10 granted, provided that the above copyright notice appear in all
  11 copies and that both that the copyright notice and this
  12 permission notice and warranty disclaimer appear in supporting
  13 documentation, and that the name of Lucent or any of its entities
  14 not be used in advertising or publicity pertaining to
  15 distribution of the software without specific, written prior
  16 permission.
  17
  18 LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  19 INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS.
  20 IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY
  21 SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  22 WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
  23 IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
  24 ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
  25 THIS SOFTWARE.
  26
  27 ****************************************************************/
  28
  29 /* Please send bug reports to David M. Gay (dmg@acm.org). */
  30
  31 #include "gdtoaimp.h"
  32 #include <string.h>
  33
  34  char *
  35 #ifdef KR_headers
  36 g_ddfmt(buf, dd, ndig, bufsize) char *buf; double *dd; int ndig; unsigned bufsize;
  37 #else
  38 g_ddfmt(char *buf, double *dd, int ndig, unsigned bufsize)
  39 #endif
  40 {
  41         FPI fpi;
  42         char *b, *s, *se;
  43         ULong *L, bits0[4], *bits, *zx;
  44         int bx, by, decpt, ex, ey, i, j, mode;
  45         Bigint *x, *y, *z;
  46         double ddx[2];
  47
  48         if (bufsize < 10 || bufsize < ndig + 8)
  49                 return 0;
  50
  51         L = (ULong*)dd;
  52         if ((L[_0] & 0x7ff00000L) == 0x7ff00000L) {
  53                 /* Infinity or NaN */
  54                 if (L[_0] & 0xfffff || L[_1]) {
  55  nanret:
  56                         return strcp(buf, "NaN");
  57                         }
  58                 if ((L[2+_0] & 0x7ff00000) == 0x7ff00000) {
  59                         if (L[2+_0] & 0xfffff || L[2+_1])
  60                                 goto nanret;
  61                         if ((L[_0] ^ L[2+_0]) & 0x80000000L)
  62                                 goto nanret;    /* Infinity - Infinity */
  63                         }
  64  infret:
  65                 b = buf;
  66                 if (L[_0] & 0x80000000L)
  67                         *b++ = '-';
  68                 return strcp(b, "Infinity");
  69                 }
  70         if ((L[2+_0] & 0x7ff00000) == 0x7ff00000) {
  71                 L += 2;
  72                 if (L[_0] & 0xfffff || L[_1])
  73                         goto nanret;
  74                 goto infret;
  75                 }
  76         if (dd[0] + dd[1] == 0.) {
  77                 b = buf;
  78 #ifndef IGNORE_ZERO_SIGN
  79                 if (L[_0] & L[2+_0] & 0x80000000L)
  80                         *b++ = '-';
  81 #endif
  82                 *b++ = '0';
  83                 *b = 0;
  84                 return b;
  85                 }
  86         if ((L[_0] & 0x7ff00000L) < (L[2+_0] & 0x7ff00000L)) {
  87                 ddx[1] = dd[0];
  88                 ddx[0] = dd[1];
  89                 dd = ddx;
  90                 L = (ULong*)dd;
  91                 }
  92         z = d2b(dd[0], &ex, &bx);
  93         if (dd[1] == 0.)
  94                 goto no_y;
  95         x = z;
  96         y = d2b(dd[1], &ey, &by);
  97         if ( (i = ex - ey) !=0) {
  98                 if (i > 0) {
  99                         x = lshift(x, i);
 100                         ex = ey;
 101                         }
 102                 else
 103                         y = lshift(y, -i);
 104                 }
 105         if ((L[_0] ^ L[2+_0]) & 0x80000000L) {
 106                 z = diff(x, y);
 107                 if (L[_0] & 0x80000000L)
 108                         z->sign = 1 - z->sign;
 109                 }
 110         else {
 111                 z = sum(x, y);
 112                 if (L[_0] & 0x80000000L)
 113                         z->sign = 1;
 114                 }
 115         Bfree(x);
 116         Bfree(y);
 117  no_y:
 118         bits = zx = z->x;
 119         for(i = 0; !*zx; zx++)
 120                 i += 32;
 121         i += lo0bits(zx);
 122         if (i) {
 123                 rshift(z, i);
 124                 ex += i;
 125                 }
 126         fpi.nbits = z->wds * 32 - hi0bits(z->x[j = z->wds-1]);
 127         if (fpi.nbits < 106) {
 128                 fpi.nbits = 106;
 129                 if (j < 3) {
 130                         for(i = 0; i <= j; i++)
 131                                 bits0[i] = bits[i];
 132                         while(i < 4)
 133                                 bits0[i++] = 0;
 134                         bits = bits0;
 135                         }
 136                 }
 137         mode = 2;
 138         if (ndig <= 0) {
 139                 if (bufsize < (int)(fpi.nbits * .301029995664) + 10) {
 140                         Bfree(z);
 141                         return 0;
 142                         }
 143                 mode = 0;
 144                 }
 145         fpi.emin = 1-1023-53+1;
 146         fpi.emax = 2046-1023-106+1;
 147         fpi.rounding = FPI_Round_near;
 148         fpi.sudden_underflow = 0;
 149         i = STRTOG_Normal;
 150         s = gdtoa(&fpi, ex, bits, &i, mode, ndig, &decpt, &se);
 151         b = g__fmt(buf, s, se, decpt, z->sign);
 152         Bfree(z);
 153         return b;
 154         }